The present invention relates to an apparatus for producing articles having a three-dimensional structure, for example, reinforced glass containers. More particularly, the present invention relates to an apparatus for forming a resin coating on the surface of an article having a three-dimensional structure.
Many glass containers are now used for selling beer or other articles in bottled form. It is preferable to minimize the wall thickness of such glass containers with a view to reducing the cost and the weight. However, if the wall thickness of glass containers is reduced excessively, the strength of the glass containers becomes weak. To reduce the wall thickness of glass containers without losing the required strength thereof, formation of a resin coating on the surface of a glass container has been studied recently. For example, European Patent Application No. 86,474 discloses a method wherein an article having a three-dimensional structure is coated with a curable resin solution, and thereafter, the resin coating is cured by irradiation with ultraviolet rays either in an inert atmosphere or in the air. The prior art literature discloses that the resin coating is cured by irradiation with ultraviolet rays in an inert atmosphere, but it contains no description about a means for preventing leakage of the inert gas and intrusion of air.
More specifically, when an ultraviolet light irradiation chamber or an electron beam irradiation chamber is maintained in an inert atmosphere (e.g., a nitrogen atmosphere), leakage of the inert gas and intrusion of air that attends the leakage must be prevented when an article to be treated is fed in and out of the irradiation chamber maintained in the inert atmosphere. If the article to be treated has a sheet-like (planar) configuration, leakage of the inert gas and intrusion of air can be readily prevented by forming a slit-shaped opening at the entrance and exit, through which the sheet-shaped article is fed in and out of the irradiation chamber. However, when an article having a three-dimensional structure, e.g., a glass bottle, is to be treated, it has heretofore been exceedingly difficult to substantially prevent leakage of the inert gas from the irradiation chamber and intrusion of air thereinto when the article is fed in and out of the irradiation chamber. For example, beer bottles vary in size and arrangement according to kinds of product. Further, when the surfaces of articles having a three-dimensional structure, e.g., glass containers are to be coated with a resin solution, it is common practice to retain a plurality (e.g., several tens) of glass containers with an article transport member and carry out coating of a resin solution, drying and curing of the resin coating for the glass containers all together in the retained state. Accordingly, there may be variations in the size and number of containers retained by the same article transport member. Therefore, it has heretofore been considered extremely difficult to prevent leakage of the inert gas from the curing chamber and intrusion of air from the outside of the chamber when such an article transport means having a complicated structure is fed in and out of the curing chamber maintained in the inert gas atmosphere. Leakage of the inert gas necessitates introduction of additional inert gas into the curing chamber, which is uneconomical. Intrusion of air causes oxidation of the unreacted resin material, lowering the degree of polymerization, and thus resulting in deterioration of the resin coating obtained.